Block artifactwhich deteriorates the video subjective visual quality especially in low bit rate is a remarkable problem which usually appears in block based c1oding system. Unlike MPEG series coding system

H.264 does not use post processing filter but adds loop filter in motion vector compensation loop. Loopfilter is based on macroblock or piece. The most essential points in loop filter are strength—a value which indicates the strength of block artifact—and filtering operators. In order to obtain better subjective visual quality

a new loopfilter arithmetic where the filtering operators are added withmore details and some other factors are added in the arithmetic of computing strengths. In the experiment

it is showed that the subjective and objective quality of video can be improved remarkably.